The solution should be CPAN grade.
Frankly, I would say that before you do anything else you should use that “C compiler that has no problems with 64-bit ints” to compile a version of Perl.   In other words, sidestep completely the issue of providing a 64-bit quantity to a Perl that can’t handle it.
........................
These days you can run 64-bit ints just as easily as you can run 32-bit; therefore, do so.
I understand you're being frank. 64 bit Windows users are currently a minority, http://www.itsnyc.com/index.php/blog/item/windows-7s-64-bit-adoption. I think you know the status and support of Perl 32 bit pointers with 64 bit ints on Windows.

In reply to Re^2: supporting quads on 32 bit Perl by bulk88
in thread supporting quads on 32 bit Perl by bulk88

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.